The Big Bang Theory


A woman who moves into an apartment across the hall from two brilliant but socially awkward physicists shows them how little they know about life outside of the laboratory.

Johnny Galecki / Jim Parsons / Kaley Cuoco-Sweeting / Simon Helberg / Kunal Nayyar / Melissa Rauch / Mayim Bialik

    • Released
    • (2007-)
    • Seasons
    • 12 seasons
    • Status
    • returning series
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    SEASON 12

  • Episode 19The Inspiration Deprivation

    The concept of what it would mean for women everywhere if Amy were to win a Nobel Prize causes Amy to have a meltdown. Also, Koothrappali and Wolowitz try to relive the good old days after Wolowitz buys a scooter that looks like the one he had years ago.

  • Episode 18The Laureate Accumulation

    When competitors Pemberton and Campbell charm America on a publicity tour, Sheldon and Amy try to bring Nobel laureates Kip Thorne, George Smoot and Frances Arnold to their side. Also, Halley's fear of the dark leads to opportunity and conflict for Howard

  • Episode 17The Conference Valuation

    When Penny and Bernadette go to San Diego for a pharmaceutical sales convention, Wolowitz is in charge of the kids. Also, Sheldon finds a book on experimenting on kids, and the guys plus Amy make a day of it.

  • Episode 16The D & D Vortex

    When the gang finds out Wil Wheaton hosts a celebrity Dungeons and Dragons game involving William Shatner, Joe Manganiello, Kareem Abdul-Jabbar and Kevin Smith, deception and betrayal are the path to make it to the one open seat.

  • Episode 15The Donation Oscillation

    Penny tries to seduce an abstaining Leonard to ruin his "donation" for her ex-boyfriend, Zack, and his wife, Marissa. Also, Wolowitz, Bernadette, Anu and Koothrappali turn Koothrappali's canceled bachelor party into a couple's trip aboard the "vomit comet

  • Episode 14The Meteorite Manifestation

    Sheldon is thrilled to help Bernadette and Wolowitz navigate bureaucratic paperwork, until he discovers they are breaking the law. Also, Leonard is disappointed when his friends exclude him from a scientific project.

  • Episode 13The Confirmation Polarization

    When Sheldon and Amy's super asymmetry theory is proven by two physicists, Dr. Pemberton and Dr. Campbell from Chicago, they're thrilled, until they try to kick Amy off the Nobel nomination. Also, Bernadette has a big success at work and Penny's going to

  • Episode 12The Propagation Proposition

    Penny's ex-boyfriend, Zack, and his wife want a baby, but when Zack is infertile, they ask Leonard for help. Also, Koothrappali attempts to mend things with his ex-fiancée, Anu.

  • Episode 11The Paintball Scattering

    Penny and Leonard organize a paintball game that results in mayhem when Sheldon is jealous of Amy. Also, Koothrappali catches Anu with her ex-boyfriend, and Stuart doesn't want to move in with Denise.

  • Episode 10The VCR Illumination

    Sheldon and Amy are still down about their theory being disproven, but a VHS tape from Sheldon's past inspires him not to give up. Also, Bernadette turns into a pageant mom when she tries to help Wolowitz ace his Magic Castle audition.

  • Episode 9The Citation Negation

    Sheldon and Amy are devastated after learning from a Russian paper that Super Asymmetry has already been discovered and disproven. Also, ultra-competitive Bernadette asks Stuart's girlfriend, Denise, to teach her how to beat Howard in a popular videogame.

  • Episode 8The Consummation Deviation

    Sheldon tries to bond with Amy's father, but when Wolowitz lures Mr. Fowler away with magic tricks, Sheldon has no choice but to bond with Mrs. Fowler. Also, Koothrappali and Anu try to get physical for the first time.

  • Episode 7The Grant Allocation Derivation

    Leonard is caught between a rock and a hard place when he's responsible for distributing extra grant money. Also, Bernadette turns the backyard playhouse into a hideaway from her husband and kids.

  • Episode 6The Imitation Perturbation

    When Wolowitz dresses up as Sheldon for Halloween, Sheldon seeks retaliation at Leonard and Penny's Halloween party. Also, Leonard is shocked that Penny doesn't remember their first kiss.

  • Episode 5The Planetarium Collision

    When Amy doesn't have time to work on super-asymmetry, Sheldon goes to great lengths to ensure she's available to work with him even it if means accidentally sabotaging her career in the process. Also, Koothrappali doesn't want Wolowitz to join him in hos

  • Episode 4The Tam Turbulence

    When Sheldon won't tell anyone why he's never mentioned Tam, his childhood best friend, Leonard takes matters into his own hands. Also, Bernadette and Penny take out Raj's fiancée, Anu, for dinner to get the skinny on her.

  • Episode 3The Procreation Calculation

    The Wolowitzes' life gets complicated when Stuart starts bringing his new girlfriend home. Also, Penny and Leonard talk about starting a family while Koothrappali explores an arranged marriage.

  • Episode 2The Wedding Gift Wormhole

    Sheldon and Amy drive themselves crazy trying to figure out what "perfect gift" Leonard and Penny gave them for their wedding. Also, Koothrappali decides he wants to settle down and asks his father to arrange a marriage for him.

  • Episode 1The Conjugal Configuration

    Sheldon and Amy's honeymoon runs aground in New York, while Penny and Leonard discover they are uncomfortably similar to Amy's parents, Mr. and Mrs. Fowler. Also, Koothrappali insults physicist Neil deGrasse Tyson and starts a Twitter war.

    SEASON 11

  • Episode 24Episode #11.24

  • Episode 23Episode #11.23

  • Episode 22Episode #11.22

  • Episode 21The Comet Polarization

    Sheldon's comic book store experience changes when writer Neil Gaiman puts Stuart's store on the map; friendships are threatened when Koothrappali takes credit for Penny's astronomical discovery.

  • Episode 20The Reclusive Potential

    Sheldon takes the guys to a cabin in the middle of nowhere to meet a reclusive scientist; Penny and Bernadette improvise Amy's bachelorette party.

  • Episode 19The Tenant Disassociation

    Leonard runs against Sheldon to be president of the tenants association; Wolowitz and Koothrappali find a drone in the backyard.

  • Episode 18The Gates Excitation

    Leonard, Howard and Raj try to meet Bill Gates, who's meeting with Penny to merge their companies; Sheldon thinks he's the victim of an April Fool's prank.

  • Episode 17The Athenaeum Allocation

    Leonard jumps through hoops to help secure the perfect wedding venue for Sheldon and Amy. Also, Bernadette and Wolowitz have a hard time deciding who should stay at home with the kids and who should go back to work.

  • Episode 16The Neonatal Nomenclature

    When Bernadette won't go into labor, the gang try different tactics to get things started. Also, Wolowitz confronts Bernadette after Amy accidentally reveals she's already chosen their son's name.

  • Episode 15The Novelization Correlation

    Leonard's book raises questions, and Amy guest stars on the new Professor Proton show.

  • Episode 14The Separation Triangulation

    Raj meets a girl who is his new love but meanwhile finds something about her that he did not realize.

  • Episode 13The Solo Oscillation

    Sheldon kicks Amy out to work solo, so she and Leonard bond during a series of science experiments; Howard is replaced by Bert in Footprints on the Moon; Penny proves to be a surprising source of scientific inspiration for Sheldon. Howard and Raj start a

  • Episode 12The Matrimonial Metric

    Sheldon and Amy pick their best-man and maid of honor, by doing tricky experiments on their friends. This causes uproar in the group. Meanwhile, Leonard's self-confidence is still badly damaged after reading his brother's Christmas letter.

  • Episode 11The Celebration Reverberation

  • Episode 10The Confidence Erosion

    Sheldon and Amy try to eliminate stress from wedding planning by applying math to the process ending up at city hall. Also, Raj "breaks up" with Howard after realizing his best friend is actually hurting his confidence.

  • Episode 9The Bitcoin Entanglement

    Sheldon tries to teach the guys a lesson after they cut him out of a potentially valuable Bitcoin investment. Also, a seven-year-old video reveals a secret about Leonard and Penny's relationship.

  • Episode 8The Tesla Recoil

    Howard and Leonard become upset after they discover that Sheldon has been working with the military without telling them; Bernadette asks Raj to investigate her suspicions that Ruchi is attempting to take her job away from her.

  • Episode 7The Geology Methodology

  • Episode 6The Proton Regeneration

    Sheldon and Wil Wheaton both go head-to-head for the role of the new Professor Proton, Meanwhile Penny takes care of Halley when Bernadette and Howard are on bed rest.

  • Episode 5The Collaboration Contamination

    Amy and Howard work in the lab together causing Sheldon, Bernadette and Raj to feel jealous and lonely. Penny and Leonard use a parenting book to control Sheldon's behavior.

  • Episode 4The Explosion Implosion

    Leonard is devastated by the new friendly relation developing between his mother and Penny. Meanwhile Sheldon takes a detour with Raj and Howard to explore the old belongings of Howard's Science Models.

  • Episode 3The Relaxation Integration

    Sheldon and Amy struggle with picking a wedding date. Amy wants it near a cliff which Sheldon doesn't want. Meanwhile Stuart and Raj fight over one of Bernadette's co-workers for a date.

  • Episode 2The Retraction Reaction

    Leonard angers the University and the Physics Community when he gives an embarrassing radio interview. Bernadette and Amy talk about their success. After the embarrassing radio interview Penny comforts her husband.

  • Episode 1The Proposal Proposal

    Amy has trouble deciding whether or not she should marry Sheldon. Meanwhile, Bernadette confides in Penny when she finds out some huge news.

    SEASON 10

  • Episode 24The Long Distance Dissonance

    The gang is concerned when Sheldon's former admirer, Dr. Ramona Nowitzki, resurfaces while Amy is away at Princeton.

  • Episode 23The Gyroscopic Collapse

    After celebrating the completion of the top-secret Air Force project, Leonard, Sheldon and Wolowitz get an unwelcome surprise; Amy receives an offer for a summer position as a visiting researcher.

  • Episode 22The Cognition Regeneration

  • Episode 21The Separation Agitation

    Howard and Bernadette have a hard time leaving Halley in daycare when Bernadette returns to work. Also, Bert introduces the gang to his new girlfriend, Rebecca.

  • Episode 20The Recollection Dissipation

    Sheldon reaches his limit when he works on projects with Leonard, Wolowitz and Amy in one day.

  • Episode 19The Collaboration Fluctuation

    Leonard, Penny and Raj adjust to their new living arrangements; Sheldon expresses an interest in Amy's work.

  • Episode 18The Escape Hatch Identification

    When the gang offers a place for Raj to live, it creates unexpected conflict among everyone and an argument between Amy and Leonard's mother.

  • Episode 17The Comic-Con Conundrum

    The guys' annual trip to Comic Con is in doubt when Raj can't afford to go.

  • Episode 16Episode #10.16

    Amy discovers everyone at the university knows about Sheldon's and her romantic encounters. Raj's contemplates trying to live without financial support from his father.

  • Episode 15The Locomotion Reverberation

    Leonard and Howard's attempt to keep Sheldon away from their Air Force project by sending him on a train trip backfires. Penny and Amy take Bernadette for her first night out since having the baby.

  • Episode 14The Emotion Detection Automation

    Penny's brother comes to town and Leonard tries to help her land him a job interview. Sheldon learns of a machine that will help him understand human emotions. Raj reunites some of his old girlfriends to figure out why he is still single.

  • Episode 13The Romance Recalibration

    Leonard and Penny ask for Sheldon's and Amy's help on putting the romance back in their marriage. Howard and Raj go to extreme lengths to stop the floor in Halley's bedroom from making noise.

  • Episode 12The Holiday Summation

    After spending the holidays apart, the gang gets together to hear about Sheldon's and Amy's trip to his mother's, Leonard's and Penny's Christmas tree adventure, and Howard's and Bernadette's first days as parents.

  • Episode 11The Birthday Synchronicity

    Amy's desire to have an intimate night with Sheldon on her birthday is interrupted by Bernadette going into labor.

  • Episode 10The Property Division Collision

    Dividing up their possessions becomes an all-out war between Leonard and Sheldon. Stuart asks to live with Howard and Bernadette and tries to supplant Raj's efforts to help with the new baby.

  • Episode 9The Geology Elevation

    Sheldon can't contain his jealousy when Bert receives a large Geology grant. A new toy Howard buys faces judgment by everyone.

  • Episode 8The Brain Bowl Incubation

    A proposition by Sheldon shocks Amy. Raj takes an interest in someone at the university.

  • Episode 7The Veracity Elasticity

    Amy neglects to tell Sheldon her apartment has been repaired. Leonard and Penny discuss what is to be done with Sheldon's room, but Leonard becomes more upset that Penny's been storing away his collectibles.

  • Episode 6The Fetal Kick Catalyst

    Sheldon and Amy host a brunch. Penny is surprised by her popularity when her movie, Serial Apeist, is featured at a Van Nuys comic book convention.

  • Episode 5The Hot Tub Contamination

    Sheldon and Amy go through a period of adjustment with their new living arrangement. Howard and Bernadette are forced to vacation at home when she falls ill and keep it a secret, unaware Raj and Stuart planned to use their hot tub.

  • Episode 4The Cohabitation Experimentation

    When Amy must vacate her apartment for repairs, living arrangements are made with Leonard, Sheldon, and Penny. Howard and Bernadette don't want to know the sex of their baby, but Raj finds out.

  • Episode 3The Dependence Transcendence

    Bernadette confides to Raj she isn't sure if she's ready to be a mother. Penny accompanies Amy to a university mixer, and Sheldon goes to unusual extremes to assist Howard with his military project.

  • Episode 2The Military Miniaturization

    Howard is visited by an Air Force captain regarding his invention. Penny tells her co-workers Bernadette is pregnant, not knowing Bernadette was trying to keep it a secret.

  • Episode 1The Conjugal Conjecture

    As Leonard and Penny attempt to hold another wedding ceremony everyone can attend, they have to deal with Penny's family arriving and Leonard's father spending the night with Sheldon's mother.

    SEASON 9

  • Episode 24The Convergence Convergence

    Leonard and Penny try to have a wedding ceremony everyone can attend, but it creates serious conflict among Sheldon's mother and Leonard's divorced parents. Howard's invention draws the attention of the Air Force.

  • Episode 23The Line Substitution Solution

    Penny has trouble when Leonard's mother comes to town. Sheldon hires Stuart to hang out with Amy while he goes to a movie screening.

  • Episode 22The Fermentation Bifurcation

    Sheldon and Bernadette spend a night together while the rest of the gang goes to a wine tasting party, but things get uncomfortable for Raj when Zack also attends and takes an interest in Claire.

  • Episode 21The Viewing Party Combustion

    A minor argument between Sheldon and Leonard escalates quickly and drags the rest of the gang into it during a "Game of Thrones" watching party..

  • Episode 20The Big Bear Precipitation

    Secrets are revealed when Amy and Sheldon join Penny and Leonard on a weekend cabin trip. Raj is more excited about Howard's and Bernadette's impending parenthood than they are.

  • Episode 19The Solder Excursion Diversion

    Amy is shocked by a revelation from Sheldon when she buys him a new laptop. Raj rats on Leonard and Howard to Penny and Bernadette.

  • Episode 18The Application Deterioration

    Sheldon works up a contract to split their portion of their guidance system invention royalties, but Bernadette does not like how it's done. Raj must again decide between Emily and Claire when they both contact him.

  • Episode 17The Celebration Experimentation

  • Episode 16The Positive Negative Reaction

    Bernadette has some news to share, but the reactions are not what is expected.

  • Episode 15The Valentino Submergence

    Sheldon and Amy host a Valentine's Day episode of "Fun with Flags", Leonard and Penny grapple with getting older, Howard and Bernadette find a surprise in their hot tub and Raj is torn between Emily and Claire.

  • Episode 14The Meemaw Materialization

    Meemaw meets Amy, but it isn't all roses. Meemaw seems to have an axe to grind with her. Sheldon comes to Amy's defense, but not before Meemaw lets a little secret of his slip.

  • Episode 13The Empathy Optimization

    After being forced to deal with a sick Sheldon, the rest of the gang try to treat themselves to a Sheldon-free weekend.

  • Episode 12The Sales Call Sublimation

    Leonard visits a psychiatrist so Penny can make a sales call on her and they learn some things about their interactions and marital issues. Stuart moves out of the Wolowitz House. Sheldon works with Raj looking for extra-solar planets.

  • Episode 11The Opening Night Excitation

  • Episode 10The Earworm Reverberation

  • Episode 9The Platonic Permutation

    On Thanksgiving, Sheldon and Amy try to spend time together as friends and go to an aquarium, Howard reluctantly agrees to volunteer at the soup kitchen with Bernadette, Raj and Emily, and ...

  • Episode 8The Mystery Date Observation

    Sheldon recruits Howard and Raj in order to find him a new girlfriend, while Bernadette, Penny and Leonard spy on Amy's mystery date.

  • Episode 7The Spock Resonance

    Wil Wheaton interviews Sheldon for a Star Trek documentary where he reveals the ring and his plan to propose to Amy. Bernadette wants to start renovating the house and the topic of starting a family together with Howard is brought up.

  • Episode 6The Helium Insufficiency

    Sheldon and Leonard find out that other scientists are trying to steal their Superfluid Helium idea. The gang try and find a new boyfriend for Amy on a new mobile dating app.

  • Episode 5The Perspiration Implementation

    The guys want to learn to be better at sports so Barry Kripke teaches them fencing. Meanwhile the girls help Stuart try to get more women to come to the comic book store. Amy gets asked out...

  • Episode 4The 2003 Approximation

    Leonard and Penny finally move in together leaving Sheldon very upset with this big change in his life and wishing he could go back to a time when he had no emotions in 2003 before he met ...

  • Episode 3The Bachelor Party Corrosion

    The guys' science skills are put to the test when they get a flat tire during Leonard's bachelor party weekend in Mexico. Meanwhile, the girls force Penny to finally tell her family that she eloped with Leonard.

  • Episode 2The Separation Oscillation

    Leonard confronts the woman he kissed on the North Sea in an attempt to set Penny's mind at ease. Meanwhile, Sheldon films a special episode of "Fun with Flags" after his breakup with Amy, ...

  • Episode 1The Matrimonial Momentum

    Penny struggles with Leonard's confession that he kissed another woman as they prepare to get married in Las Vegas. Meanwhile, Sheldon doesn't know what to do after Amy pushes pause on their relationship.

    SEASON 8

  • Episode 24The Commitment Determination

    As Sheldon presses Leonard and Penny to set a wedding date, he encounters major changes in his relationship with Amy.

  • Episode 23The Maternal Combustion

    Personalities collide when Leonard and Sheldon's mothers finally meet. Meanwhile, Howard finally decides to "man up" and do his fair share of the housework - but not without a little help from his friends.

  • Episode 22The Graduation Transmission

    When Leonard's flight to his alma mater is canceled, he uses any and all means to deliver the speech he was asked to give. Raj's father threatens to cut off his money, and Sheldon and Howard try to fix a helicopter drone.

  • Episode 21The Communication Deterioration

    When Raj is asked to create a message on the off chance a NASA mission discovers alien life, the guys fight over what he should do, while Penny contemplates returning to acting.

  • Episode 20The Fortification Implementation

    When Sheldon and Amy build a blanket fort, they come to major crossroads in their relationship. Meanwhile, Howard meets the half-brother he never knew he had, and Penny is invited to appear on Wil Wheaton's podcast.

  • Episode 19The Skywalker Incursion

    When Leonard and Sheldon are invited to speak at UC Berkeley, they take a detour to try and meet one of their idols. Meanwhile, while cleaning out Mrs. Wolowitz's house, a ping pong battle ...

  • Episode 18The Leftover Thermalization

    Tension arises when a magazine fails to mention Leonard in an article about the paper he co-wrote with Sheldon, and a blackout at Mrs. Wolowitz's home leads to a final family dinner in her honor.

  • Episode 17The Colonization Application

    A trip to the pet store ends in a fight after Amy learns Sheldon has applied for a one-way mission to colonize Mars. Meanwhile, Leonard surprises Penny with a very "adult" purchase, and Raj gets into trouble when he snoops around Emily's apartment.

  • Episode 16The Intimacy Acceleration

    Sheldon and Penny agree to participate in an unusual experiment. Leonard, Amy, Raj and Emily spend the evening trying to escape a room with a "zombie". Howard and Bernadette run into trouble at the airport after returning from Mrs. Wolowitz's funeral.

  • Episode 15The Comic Book Store Regeneration

    Howard receives some shocking news as everyone prepares for the re-opening of the comic book store. Meanwhile, Penny tries to teach Sheldon how to "let it go," but can't follow her own advice when she learns something infuriating about Amy.

  • Episode 14The Troll Manifestation

    Leonard and Sheldon defend themselves against criticism from an online bully, while the girls confront embarrassing moments from their pasts.

  • Episode 13The Anxiety Optimization

    When Sheldon becomes stuck in a rut with his work, the gang try to help him by raising his stress levels. Howard teases Raj with a game called "Emily or Cinnamon."

  • Episode 12The Space Probe Disintegration

    Raj worries a probe he designed will not work in outer space, while Leonard and Sheldon go shopping with Penny and Amy.

  • Episode 11The Clean Room Infiltration

    Amy hosts a traditional Victorian Christmas Eve dinner, Raj's father comes to visit, and the guys try to shoo out a bird they let into the university clean room.

  • Episode 10The Champagne Reflection

    While Sheldon retires "Fun With Flags", Leonard, Howard and Raj look for something significant in a dead professor's research, and Bernadette finds out what her colleagues really think of her.

  • Episode 9The Septum Deviation

    Sheldon panics when Leonard announces he has to go into the hospital for surgery. Raj discovers his parents have divorced.

  • Episode 8The Prom Equivalency

    The girls decide to re-enact their high school proms with the guys. While Sheldon feels under pressure to commit to his relationship with Amy, Howard worries about who Stuart will bring as his date.

  • Episode 7The Misinterpretation Agitation

    The guys befriend one of Penny's clients when he shows up at her apartment. Meanwhile, Bernadette gets upset when Amy torpedoes an article about her for a local magazine.

  • Episode 6The Expedition Approximation

    Sheldon and Raj test whether they could survive a dark-matter research expedition in a salt mine by simulating the conditions in a steam tunnel. Meanwhile, Leonard and Penny seek advice from Howard and Bernadette when they argue about money.

  • Episode 5The Focus Attenuation

    The girls head to Vegas, while the guys try to invent something cool, but only come up with new ways to procrastinate.

  • Episode 4The Hook-up Reverberation

    Raj's honesty about his past comes back to haunt him after Emily takes a dislike to Penny. Meanwhile, the guys consider investing in the comic book store.

  • Episode 3The First Pitch Insufficiency

    Howard becomes nervous after NASA asks him to throw out the first pitch at a Los Angeles Angels game. Meanwhile, Leonard and Penny try to prove Sheldon wrong when he says that he and Amy have a 'superior' relationship.

  • Episode 2The Junior Professor Solution

    Sheldon is forced to teach a class as a Junior Professor. Meanwhile, the tension between Penny and Bernadette gives Amy a chance to play both sides.

  • Episode 1The Locomotion Interruption

    Sheldon's trip comes to an end when he is robbed, Penny interviews for a job at Bernadette's company, and Howard is weirded out by his mother's relationship with Stuart.

    SEASON 7

  • Episode 24The Status Quo Combustion

    Sheldon gets upset about his career, the destruction of the comic book store and Leonard and Penny's future living arrangements. Howard and Bernadette struggle to keep hold of a caregiver for Mrs. Wolowitz.

  • Episode 23The Gorilla Dissolution

    Penny gets fired from her movie and takes a serious look at her life. Raj sees Emily on a date with another man at the movies. Howard and Bernadette have to take care of his mother after she breaks her leg.

  • Episode 22The Proton Transmogrification

    As the gang celebrate Star Wars Day, Sheldon has difficulty dealing with the recent death of Arthur "Professor Proton" Jeffries.

  • Episode 21The Anything Can Happen Recurrence

    When Sheldon tries to be spontaneous, it leads to unexpected friction between the girls. Meanwhile, Raj seeks Howard's help in preparing for a date with Emily.

  • Episode 20The Relationship Diremption

    Penny tries to help Sheldon when he reconsiders his "relationship" with String Theory. During a dinner with Howard and Bernadette, Raj discovers Howard once embarrassed himself on a date with Emily.

  • Episode 19The Indecision Amalgamation

    While Raj is wracked with guilt when he tries to date Lucy and Emily at the same time, Penny wrestles with whether to take a role in a cheesy movie and Sheldon is torn trying to choose between two gaming systems.

  • Episode 18The Mommy Observation

    When Sheldon visits his mother in Houston, he is forced to confront a new reality. Back in Pasadena, the rest of the gang reluctantly take part in Raj's Murder Mystery party.

  • Episode 17The Friendship Turbulence

    After arguing with Sheldon, Howard tries to make amends by taking him to NASA headquarters in Houston. Penny has second thoughts about quitting her waitressing job when her car dies. Amy gets involved in trying to find Raj a date.

  • Episode 16The Table Polarization

    Leonard's purchase of a dining room table causes Sheldon to reevaluate the changes in his life. Meanwhile, Howard is offered a chance to go back to space and Bernadette struggles with whether or not to encourage him.

  • Episode 15The Locomotive Manipulation

    Sheldon and Amy take a train ride to Napa Valley with Howard and Bernadette on Valentine's Day. Leonard and Penny take Raj's dog to the vet when she accidentally eats some chocolate.

  • Episode 14The Convention Conundrum

    When the guys can't get hold of any Comic-Con tickets, Sheldon tries to hold his own convention and winds up spending a wild night with James Earl Jones. The girls go to a hotel for tea and talk about maturity.

  • Episode 13The Occupation Recalibration

    Sheldon tries to relax after he is forced to take a vacation. Leonard struggles to be supportive of Penny after she quits her job. Amy receives unwanted attention from a co-worker. Bernadette seeks Stuart's help in replacing one of Howard's comic books.

  • Episode 12The Hesitation Ramification

    After Leonard tries to help Penny following a failed role on a TV show, she makes an important decision. Meanwhile, Raj and Stuart try to practice their social skills, and Sheldon navigates the intricacies of being funny.

  • Episode 11The Cooper Extraction

    While Sheldon is at home in Texas, the rest of the gang decorate for Christmas and think about how much he has affected their lives.

  • Episode 10The Discovery Dissipation

    Leonard has to deal with the fallout of disproving Sheldon's new scientific discovery. Raj spends a week at Howard and Bernadette's apartment.

  • Episode 9The Thanksgiving Decoupling

    The gang spend Thanksgiving at Mrs. Wolowitz's house. Howard tries to bond with his father-in-law, and a mistake from Penny's past comes back to haunt her.

  • Episode 8The Itchy Brain Simulation

    Sheldon demands Leonard make up for a mistake from their past. Penny confronts Raj's ex-girlfriend, Lucy.

  • Episode 7The Proton Displacement

    Sheldon seeks payback when Arthur "Professor Proton" Jeffries asks Leonard for help on a project instead of him. Raj gets upset at Howard for crashing his night with the girls.

  • Episode 6The Romance Resonance

    Howard tries to do something special to celebrate the anniversary of his first date with Bernadette. Sheldon is conflicted when he makes a major scientific breakthrough but some details have to be corrected.

  • Episode 5The Workplace Proximity

    After a fight with Bernadette, Howard ends up on Raj's couch. Sheldon and Amy clash when Amy takes a job at the university.

  • Episode 4The Raiders Minimization

    Sheldon gets mad at Amy for ruining one of his favorite movies, Raj and Stuart try to make their online dating profiles more appealing, and Leonard tries to play the sympathy card with Penny.

  • Episode 3The Scavenger Vortex

    The gang get competitive when they are forced to take part in Raj's scavenger hunt.

  • Episode 2The Deception Verification

    Sheldon feels betrayed when Leonard returns from the North Sea and wants to spend his time with Penny instead of him. Howard's latest foray into helping his mother has some disastrous side effects.

  • Episode 1The Hofstadter Insufficiency

    Sheldon and Penny bond over missing Leonard. Howard tries to help Raj get over his breakup with Lucy. Amy and Bernadette take a trip together to a biology convention.

    SEASON 6

  • Episode 24The Bon Voyage Reaction

    Penny is thrown for a loop when Leonard is offered a job overseas, but the news is an even bigger shock to Sheldon. Raj and Lucy's relationship comes to a crossroad.

  • Episode 23The Love Spell Potential

    A date between Raj and Lucy takes both of them out of their comfort zones. After a trip to Las Vegas goes awry, the girls join in on a Dungeons and Dragons game, which causes Amy and Sheldon to re-evaluate their relationship.

  • Episode 22The Proton Resurgence

    Bernadette and Howard offer to watch Raj's dog and live to regret it. Leonard and Sheldon hire their favorite childhood star to make an appearance.

  • Episode 21The Closure Alternative

    Amy tries to help a depressed Sheldon find closure when one of his favorite TV shows is canceled. Raj becomes paranoid when he finds Lucy's blog.

  • Episode 20The Tenure Turbulence

    Leonard, Sheldon and Raj battle for tenure at the university and drag Penny and Amy into the fight.

  • Episode 19The Closet Reconfiguration

    Howard becomes upset when Sheldon finds a letter from his estranged father whilst cleaning out his and Bernadette's closet.

  • Episode 18The Contractual Obligation Implementation

    Leonard, Sheldon and Howard give lectures on science to junior high students. The girls ditch work to go to Disneyland. Raj devises a date for Lucy that fixes their social anxiety problems.

  • Episode 17The Monster Isolation

    Raj falls apart after his date sneaks out on him, and Sheldon reluctantly returns the favor after Penny helps him out with his "Fun With Flags" program.

  • Episode 16The Tangible Affection Proof

    Sheldon gets Alex to buy a Valentine's Day gift for Amy. Leonard and Penny and Howard and Bernadette have a disastrous dinner together. Raj and Stuart host a "Lonely People" party at the comic book store.

  • Episode 15The Spoiler Alert Segmentation

    Leonard moves in with Penny after a fight with Sheldon, which causes Amy to want to move in with Sheldon. Meanwhile, Raj has a frightening experience with Howard's mother.

  • Episode 14The Cooper/Kripke Inversion

    Sheldon is forced to work with Kripke on a project and must concoct an elaborate lie when he can't hold up his end of the work. Howard and Raj get superhero figurines made of themselves.

  • Episode 13The Bakersfield Expedition

    The guys are stranded in the middle of nowhere when Leonard's car is stolen on the way to the Bakersfield Comic-Con. Back home, the girls try to figure out why the guys are so fascinated with comic books.

  • Episode 12The Egg Salad Equivalency

    When Penny finds out Alex has a crush on Leonard, Sheldon gets himself and the rest of the guys in trouble with Human Resources whilst trying to solve the problem.

  • Episode 11The Santa Simulation

    The girls take Raj out to a nightclub to find him a date. A game of Dungeons and Dragons rekindle old memories of Santa for Sheldon.

  • Episode 10The Fish Guts Displacement

    Howard tries to bond with Bernadette's father during a fishing trip. When Sheldon is obligated to take care of a sick Amy, she finds ways to take advantage of the situation.

  • Episode 9The Parking Spot Escalation

    The gang are drawn into a fight between Howard and Sheldon over Sheldon's vacant parking spot at the university.

  • Episode 8The 43 Peculiarity

    Leonard feels threatened after hearing about Penny's study partner at school, while Howard and Raj become determined to find out one of Sheldon's secrets.

  • Episode 7The Habitation Configuration

    Howard makes a decision whether or not to move out of his mother's house, while Sheldon is caught in the middle of an argument between Amy and Wil Wheaton.

  • Episode 6The Extract Obliteration

    Penny enrolls in a college class and keeps it a secret from Leonard. Sheldon causes conflict with Dr. Stephen Hawking over an online game.

  • Episode 5The Holographic Excitation

    While Raj plans Stuart's Halloween party at the comic book store, Howard annoys the rest of the gang by constantly talking about space, and Penny tries to take more of an interest in Leonard's work.

  • Episode 4The Re-Entry Minimization

    Howard is offended when his return from space is met with little fanfare. Penny and Amy take on Sheldon and Leonard during game night.

  • Episode 3The Higgs Boson Observation

    When Sheldon hires a female grad student to assist him, a jealous Amy asks Penny to help her spy on them. On the space station, Howard begins behaving erratically.

  • Episode 2The Decoupling Fluctuation

    Penny continues to have doubts about her relationship with Leonard. Meanwhile, Howard becomes the target of practical jokes on the space station.

  • Episode 1The Date Night Variable

    Raj crashes Sheldon and Amy's second anniversary and interferes in Leonard and Penny's relationship. Howard gets caught in the middle of an argument between Bernadette and his mother.

    SEASON 5

  • Episode 24The Countdown Reflection

    As Howard prepares for his mission into space, flashbacks show the recent events leading up to his and Bernadette's wedding.

  • Episode 23The Launch Acceleration

    Howard faces double trouble when NASA moves up his launch and he has to meet Bernadette's father. Leonard inadvertently jeopardises his relationship with Penny.

  • Episode 22The Stag Convergence

    The guys throw Howard a bachelor party, and some embarrassing details about his life get posted on the Internet.

  • Episode 21The Hawking Excitation

    Sheldon uses any and all means to meet his hero, Dr. Stephen Hawking.

  • Episode 20The Transporter Malfunction

    Raj gets quite a surprise when he asks his parents to set him up on a date. Penny buys Leonard and Sheldon a pair of Star Trek keepsake collectibles.

  • Episode 19The Weekend Vortex

    Sheldon has to choose between joining Amy at her aunt's birthday party or playing videogames all weekend with the guys.

  • Episode 18The Werewolf Transformation

    Sheldon wreaks havoc when he tries to get a haircut from his regular barber, who is ill. Howard runs into a few problems with astronaut training.

  • Episode 17The Rothman Disintegration

    Sheldon battles Kripke for a coveted office at the university. Penny receives a very unusual gift from Amy.

  • Episode 16The Vacation Solution

    When the university forces Sheldon to use vacation days, he decides to hang out in Amy's lab. Howard becomes upset when he hears Bernadette wants him to sign a prenuptial agreement.

  • Episode 15The Friendship Contraction

    Leonard signs out of his roommate agreement, reducing himself and Sheldon to mere acquaintances, while Howard tries to think of a cool astronaut nickname for himself.

  • Episode 14The Beta Test Initiation

    Leonard and Penny develop a system to ensure their dates go smoothly. Raj finally finds a woman he can talk to - the virtual assistant on his mobile phone.

  • Episode 13The Recombination Hypothesis

    Leonard and Penny contemplate reviving their romantic relationship.

  • Episode 12The Shiny Trinket Maneuver

    Penny helps Sheldon work on his relationship with Amy when he trivializes one of her accomplishments. Howard is irked by Bernadette's dislike of children.

  • Episode 11The Speckerman Recurrence

    Leonard confronts the man who bullied him in high school, while Penny realizes she did her fair share of tormenting in the past.

  • Episode 10The Flaming Spittoon Acquisition

    When Stuart asks Amy on a date, Sheldon considers having a more serious relationship with her. Meanwhile, the guys become obsessed with a new card game involving Wild West heroes and witches.

  • Episode 9The Ornithophobia Diffusion

    Sheldon tries to overcome his fear of birds, while Leonard and Penny attempt to hang out together strictly as friends.

  • Episode 8The Isolation Permutation

    Amy is hurt when Penny and Bernadette go bridesmaid dress shopping without her, so she turns to a reluctant Sheldon for comfort.

  • Episode 7The Good Guy Fluctuation

    Sheldon tries to get into the spirit of Halloween by trying to scare the guys after they prank him. Leonard seeks Penny's advice when an attractive comic book artist takes an interest in him.

  • Episode 6The Rhinitis Revelation

    Sheldon gets upset when his mother comes to visit but refuses to cook for him and attend physics lectures.

  • Episode 5The Russian Rocket Reaction

    Sheldon takes offense when Leonard wants to attend a party with Wil Wheaton, while Bernadette tries to block Howard's opportunity to go into outer space.

  • Episode 4The Wiggly Finger Catalyst

    Penny sets up Raj with a deaf friend, not knowing that she's actually a gold digger, and Sheldon decides to let his minor decisions rest on the roll of the dice.

  • Episode 3The Pulled Groin Extrapolation

    Leonard accompanies Amy to a colleague's wedding. Howard tries to convince Bernadette to live with his mother after they get married.

  • Episode 2The Infestation Hypothesis

    Amy gets inadvertently caught in the middle of a fight between Sheldon and Penny over a chair. Leonard tries to add some spice to his long-distance relationship with Priya.

  • Episode 1The Skank Reflex Analysis

    The gang deal with the fallout from Penny and Raj's night together. Amy counsels Penny when she considers moving back to Nebraska, Bernadette confronts Raj about his crush on her, and Sheldon takes charge of the paintball team.

    SEASON 4

  • Episode 24The Roommate Transmogrification

    Raj moves in with Sheldon after hearing Leonard and Priya engage in a Star Trek fantasy in his apartment. Bernadette receives her doctorate.

  • Episode 23The Engagement Reaction

    Howard believes that his mom suffered a heart attack because he told her that he's marrying Bernadette, Sheldon freaks out over germs, and Penny and Priya bond.

  • Episode 22The Wildebeest Implementation

    Sheldon invents a three-player chess game, Penny and Amy use Bernadette to spy on Leonard and Priya, and Raj tries a new drug to treat his social anxiety.

  • Episode 21The Agreement Dissection

    When Priya finds a loophole in the roommate agreement to throw Sheldon out for the night, Penny, Amy and Bernadette take him to a nightclub.

  • Episode 20The Herb Garden Germination

    Sheldon and Amy secretly experiment on the gang by spreading rumors when they hear that Bernadette is thinking about breaking up with Howard.

  • Episode 19The Zarnecki Incursion

    The guys go all out to help Sheldon find the person responsible for hacking his online gaming account, while the girls' hatred for Priya increases.

  • Episode 18The Prestidigitation Approximation

    Priya forces Leonard to choose between a relationship with her or a friendship with Penny. A magic trick by Howard has Sheldon fooled.

  • Episode 17The Toast Derivation

    Sheldon becomes concerned when everybody begins to hang out at Raj's apartment and discovers Leonard is the center of the group.

  • Episode 16The Cohabitation Formulation

    Bernadette makes Howard choose between herself and his mother, while Penny and Raj become upset when Leonard and Priya start dating.

  • Episode 15The Benefactor Factor

    To secure needed funding for the university, Sheldon convinces Leonard to get friendly with a wealthy benefactor.

  • Episode 14The Thespian Catalyst

    To improve his skills as an instructor, Sheldon asks Penny to give him acting lessons. Meanwhile, Raj begins having impure fantasies about Bernadette.

  • Episode 13The Love Car Displacement

    Chaos ensues when the gang spend the weekend together at a science convention.

  • Episode 12The Bus Pants Utilization

    Leonard has an idea for a new smartphone app and asks the guys for help, however Sheldon tries to take over the project, and Leonard fires him.

  • Episode 11The Justice League Recombination

    The guys enter a costume contest as members of the Justice League and convince Penny and Zack to join them.

  • Episode 10The Alien Parasite Hypothesis

    Amy finds she has sexual feelings for Penny's ex-boyfriend Zack, while Raj and Howard try to prove who would be the better superhero.

  • Episode 9The Boyfriend Complexity

    Penny asks Leonard to pose as her boyfriend when her father visits. Howard, Raj and Bernadette have an awkward encounter when they spend the evening together.

  • Episode 8The 21-Second Excitation

    The guys camp out all night waiting to see an extended cut of Indiana Jones, while Penny and Bernadette invite Amy to her first slumber party.

  • Episode 7The Apology Insufficiency

    An FBI agent interviews the guys when Howard needs to obtain a security clearance.

  • Episode 6The Irish Pub Formulation

    Leonard tries to keep everyone from finding out that he spent the night with Raj's sister, but Sheldon finds out and concocts an elaborate story to help him keep the secret from Raj.

  • Episode 5The Desperation Emanation

    Sheldon is scared that he is in a relationship when Amy asks him to meet her mother, and Leonard asks Howard and Bernadette to set him up because he is the only person in the group without a girlfriend.

  • Episode 4The Hot Troll Deviation

    Howard tries to get Penny's help in winning back Bernadette, but first has to confess the embarrassing reason why they broke up in the first place. Raj and Sheldon clash over a desk.

  • Episode 3The Zazzy Substitution

    Following his 'breakup' with Amy, the gang become concerned with Sheldon's obsessive search for non-human companionship and call his mother to intervene.

  • Episode 2The Cruciferous Vegetable Amplification

    When Sheldon calculates the technology to download his consciousness into a robot won't be invented soon enough, he desperately tries to find a way to increase his lifespan.

  • Episode 1The Robotic Manipulation

    Penny ends up tagging along on Sheldon's first ever date with Amy, while Howard finds an unusual use for a robotic arm.

    SEASON 1

  • Episode 17The Tangerine Factor

    After a bad breakup, Penny finally agrees to go out on a date with Leonard, however they both develop doubts and turn to Sheldon for advice.

  • Episode 16The Peanut Reaction

    When Penny learns that Leonard has never had a birthday party, she and the rest of the guys plan a surprise party for him.

  • Episode 15The Pork Chop Indeterminacy

    Leonard, Howard and Raj fight over Sheldon's twin sister when she arrives in town. Raj takes part in a drug trial to suppress his selective mutism.

  • Episode 14The Nerdvana Annihilation

    Penny gets mad at the guys when their full scale model of a time machine causes her to miss work, which prompts Leonard to give up all of his nerd memorabilia.

  • Episode 13The Bat Jar Conjecture

    Sheldon becomes so intent on demonstrating his intellectual superiority over the other guys that they kick him off the Physics Bowl team and replace him with his nemesis, Leslie.

  • Episode 12The Jerusalem Duality

    Sheldon decides to give up his work and focus on other tasks when a 15-year-old prodigy joins the lab, so the other guys come up with a plan to get rid of him.

  • Episode 11The Pancake Batter Anomaly

    When Sheldon gets sick, Leonard, Howard and Raj go AWOL, leaving a reluctant Penny to deal with him.

  • Episode 10The Loobenfeld Decay

    Leonard lies to Penny so that he and Sheldon can get out of watching her perform. However, Sheldon believes that the lie has too many loose ends, so he comes up with a new, unnecessarily complex one to replace it.

  • Episode 9The Cooper-Hofstadter Polarization

    Leonard and Sheldon's friendship is put to the test when Leonard wants to present a paper they co-authored at a physics convention, but Sheldon doesn't.

  • Episode 8The Grasshopper Experiment

    When Raj's parents set him up on a blind date, he finds he can talk to women with the aid of alcohol.

  • Episode 7The Dumpling Paradox

    When Howard hooks up with Penny's old friend, his absence in the gang causes problems for the rest of the guys.

  • Episode 6The Middle Earth Paradigm

    The guys are invited to Penny's Halloween party, where Leonard has yet another run-in with Penny's ex-boyfriend Kurt.

  • Episode 5The Hamburger Postulate

    Leslie seduces Leonard, but afterwards tells him that she is only interested in a one-night stand.

  • Episode 4The Luminous Fish Effect

    Sheldon's mother is called to intervene when he delves into numerous obsessions after being fired for being disrespectful to his new boss.

  • Episode 3The Fuzzy Boots Corollary

    Leonard gets upset when he discovers that Penny is seeing a new guy, so he tries to trick her into going on a date with him.

  • Episode 2The Big Bran Hypothesis

    Penny is furious with Leonard and Sheldon when they sneak into her apartment and clean it while she is sleeping.

  • Episode 1Pilot

    A pair of socially awkward theoretical physicists meet their new neighbor Penny, who is their polar opposite.